Charging system issues with my 1988 XJ40
#1
05-16-2013, 03:53 PM
Charging system issues with my 1988 XJ40
A question for someone with electrical system knowledge, on a 1988 XJ40
The battery will drain on its own (Jag gremlins I think)
Volts, key out, 12.70
Volts, initial start, 12.06
Volts, after revving engine to 1700 rpm, 14.19 (this stays after the rpm drops back to idle)
Volts, with full load, 12.45 (once load is removed voltageis back to 14.19)
I have been looking at the forum for similar problems butnot seeing any.
I have removed the alternator and had it rebuilt (as long asit was out) and changed the belts, and put in a new battery (old one had abroken positive post)
Could this possibly have something to do with the" LoadDump Module" ??
Any ideas would be very much appreciated
The battery will drain on its own (Jag gremlins I think)
Volts, key out, 12.70
Volts, initial start, 12.06
Volts, after revving engine to 1700 rpm, 14.19 (this stays after the rpm drops back to idle)
Volts, with full load, 12.45 (once load is removed voltageis back to 14.19)
I have been looking at the forum for similar problems butnot seeing any.
I have removed the alternator and had it rebuilt (as long asit was out) and changed the belts, and put in a new battery (old one had abroken positive post)
Could this possibly have something to do with the" LoadDump Module" ??
Any ideas would be very much appreciated
#2
05-16-2013, 06:01 PM
Senior Member
HI,
I have some knowledge, mine is an 89 base model. Sounds to me like you have a parasitic draw rather than a charging issue.
If you're confident the alternator is good, as it sounds like it from your readings, and the battery is new, I would think you have a circuit draining your battery while at rest.
If you meter has capabilities to monitor miliamps, then you will need to disconnect your negative cable and put your meter leads on the negative battery terminal and the negative cable (use mini clamps or wire ties to keep them in place). Wait till the car is completely at rest (doors closed, engine off, courtesy lamps out), then meter the amp draw. You should be in the area of .045 ma (or lower) with the car completely at rest. If you reading is above that, or above .050 (which is high), then you probably have something on one of the circuits misbehaving. Some people may actually have lower readings at rest depending on model and features.
If this is the case (high draw), you will need to position the meter so you can view it from inside the vehicle. Get in the car, wait for at least a minute after you shut the door and ensure the ma reading has stabilized, then start methodically pulling one fuse at a time from all the fuse blocks. Don't be in a rush, might be a second or more before you see a reaction on the meter.
I'm dealing with the same issue right now. The difference with mine was that it was an intermittent draw and was difficult to track down. It finally acted up again yesterday and it's the #10 fuse on the passenger block...... just my luck..there's about seven or eight components on the circuit, so I'll have to eliminate each one to find the culprit.
Either way, you will need to either prove or eliminate the parasitic draw theory in order to move to a corrective action.
Hopefully yours will be easier to find.
I have some knowledge, mine is an 89 base model. Sounds to me like you have a parasitic draw rather than a charging issue.
If you're confident the alternator is good, as it sounds like it from your readings, and the battery is new, I would think you have a circuit draining your battery while at rest.
If you meter has capabilities to monitor miliamps, then you will need to disconnect your negative cable and put your meter leads on the negative battery terminal and the negative cable (use mini clamps or wire ties to keep them in place). Wait till the car is completely at rest (doors closed, engine off, courtesy lamps out), then meter the amp draw. You should be in the area of .045 ma (or lower) with the car completely at rest. If you reading is above that, or above .050 (which is high), then you probably have something on one of the circuits misbehaving. Some people may actually have lower readings at rest depending on model and features.
If this is the case (high draw), you will need to position the meter so you can view it from inside the vehicle. Get in the car, wait for at least a minute after you shut the door and ensure the ma reading has stabilized, then start methodically pulling one fuse at a time from all the fuse blocks. Don't be in a rush, might be a second or more before you see a reaction on the meter.
I'm dealing with the same issue right now. The difference with mine was that it was an intermittent draw and was difficult to track down. It finally acted up again yesterday and it's the #10 fuse on the passenger block...... just my luck..there's about seven or eight components on the circuit, so I'll have to eliminate each one to find the culprit.
Either way, you will need to either prove or eliminate the parasitic draw theory in order to move to a corrective action.
Hopefully yours will be easier to find.
#4
10-31-2016, 01:16 PM
HI,
I have some knowledge, mine is an 89 base model. Sounds to me like you have a parasitic draw rather than a charging issue.
If you're confident the alternator is good, as it sounds like it from your readings, and the battery is new, I would think you have a circuit draining your battery while at rest.
If you meter has capabilities to monitor miliamps, then you will need to disconnect your negative cable and put your meter leads on the negative battery terminal and the negative cable (use mini clamps or wire ties to keep them in place). Wait till the car is completely at rest (doors closed, engine off, courtesy lamps out), then meter the amp draw. You should be in the area of .045 ma (or lower) with the car completely at rest. If you reading is above that, or above .050 (which is high), then you probably have something on one of the circuits misbehaving. Some people may actually have lower readings at rest depending on model and features.
If this is the case (high draw), you will need to position the meter so you can view it from inside the vehicle. Get in the car, wait for at least a minute after you shut the door and ensure the ma reading has stabilized, then start methodically pulling one fuse at a time from all the fuse blocks. Don't be in a rush, might be a second or more before you see a reaction on the meter.
I'm dealing with the same issue right now. The difference with mine was that it was an intermittent draw and was difficult to track down. It finally acted up again yesterday and it's the #10 fuse on the passenger block...... just my luck..there's about seven or eight components on the circuit, so I'll have to eliminate each one to find the culprit.
Either way, you will need to either prove or eliminate the parasitic draw theory in order to move to a corrective action.
Hopefully yours will be easier to find.
I have some knowledge, mine is an 89 base model. Sounds to me like you have a parasitic draw rather than a charging issue.
If you're confident the alternator is good, as it sounds like it from your readings, and the battery is new, I would think you have a circuit draining your battery while at rest.
If you meter has capabilities to monitor miliamps, then you will need to disconnect your negative cable and put your meter leads on the negative battery terminal and the negative cable (use mini clamps or wire ties to keep them in place). Wait till the car is completely at rest (doors closed, engine off, courtesy lamps out), then meter the amp draw. You should be in the area of .045 ma (or lower) with the car completely at rest. If you reading is above that, or above .050 (which is high), then you probably have something on one of the circuits misbehaving. Some people may actually have lower readings at rest depending on model and features.
If this is the case (high draw), you will need to position the meter so you can view it from inside the vehicle. Get in the car, wait for at least a minute after you shut the door and ensure the ma reading has stabilized, then start methodically pulling one fuse at a time from all the fuse blocks. Don't be in a rush, might be a second or more before you see a reaction on the meter.
I'm dealing with the same issue right now. The difference with mine was that it was an intermittent draw and was difficult to track down. It finally acted up again yesterday and it's the #10 fuse on the passenger block...... just my luck..there's about seven or eight components on the circuit, so I'll have to eliminate each one to find the culprit.
Either way, you will need to either prove or eliminate the parasitic draw theory in order to move to a corrective action.
Hopefully yours will be easier to find.
I am suspecting one of the right side Relay to be the culprit as it is always a little bit warm.
I read somewhere that the protection of the copper thin wire of the relay coil can progressively loose its protection function thus creating some sort of a short circuit.
If one confirm that no one relay should be warm after a long time for the car inactivity then the warm relay should be changed.
Cheers
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